FANUC Technical Support – Zero Return Troubleshooting
* WARNING *
Use extreme caution while working with or near any moving parts or electrical components. Fatal voltages may exist on the control components. Make sure to DISCONNECT POWER before attempting any FANUC service, for your safety.
| Machine Model: Problem: |
Diagnostic procedures and possible solutions |
| 6TA/B
Machine will not zero return: |
When the machine zero returns, does it decel? If not, check the decel switch. To check the decel switch – push the decel switch down and check diagnostic #32 bit 5 for X axis and #33 bit 5 for Z axis. If it changes from 1 to a 0 when the switch is depressed, the switch is good. If the machine does decel, jog the machine away from home position – turn the rapid override switch down – try to zero return the machine and have someone depress the decel switch – (USE CAUTION…DON’T PINCH YOUR FINGERS!) the machine should slow down – let the switch back up – the machine should find home within one rev of the ball screw. If it does not, you have a bad encoder or a broken cable. You can test the cable by checking between pins: 14——-F 15——-G If the machine does home in the middle of travel – try moving the decel dog. |
| 6MA/B
Machine will not zero return: |
When the machine zero returns, does it decel? If not, check the decel switch. To check the decel switch – push the decel switch down and check diagnostic #32 bit 5 for X axis, #33 bit 5 for Y axis and #34 bit 5 for Z axis. If it changes from 1 to a 0 when the switch is depressed, the switch is good. If the machine does decel, jog the machine away from home position – turn the override switch down – try to zero return the machine and have someone depress the decel switch – (USE CAUTION…DON’T PINCH YOUR FINGERS!) the machine should slow down – let the switch back up – the machine should find home within one rev of the ball screw. If it does not, you have a bad encoder or a broken cable. You can test the cable by checking between pins: 14——-F 15——-G If the machine does home in the middle of travel – try moving the decel dog. |
| Machine gets a soft alarm when trying to zero return: | Command a G23 in MDI then zero return the machine. |
| Machine will not power up: | Look for the input unit, is the green LED on? – if not check for 220VAC on the terminal strip – if 220VAC is present you probably have a bad input unit. Is the 220VAC present? Check machine wiring. If the green LED is on and the red LED comes on when the power on push button is pushed, turn off the control – Disconnect the outputs from the power supply (these are all the connections on the right-hand side of the power supply). Turn the control on – if the red LED comes on, you probably have a bad power supply. If it does not come on you probably have a short on the machine. Connect all the 0v connections then connect one wire at a time. Turn the control on each time and see if the red LED comes on. When the red LED comes on, the last wire you hooked up has the short on it. Trace this wire to find the short. |
| RS232 Problems | If data is not being input/output or you have a communication alarm. Check the following:1) Check cable connections (see cable connections below)RS232 Connection for Fanuc Controls DB25F DB25M2 ————————————————— 3 3 ————————————————— 2 7 ————————————————— 7 Jumper Jumper 4-5 4-5 6-8-20 6-8-20 |
Contact FANUC Parts Provider for more information or for a quote on FANUC spare parts.
